Hi everyone,
This is a question for all of you salsa experts out there. Are there any exercises you recommend, aside from dancing salsa, to improve your dancing techniques, posture and speed? Do you recommend doing weight training to strengthen leg and core muscles, or should you focus more on cardio?

Dancing strains body muscles, joints etc. Hence the likelihood of injury especially if the muscles are cold. I dont think exercise (weight training, cardio) will improve one's dancing but it will help preventing any injury during dancing.

I feel this is one topic which one should not neglect. Body warm-up and exercise will be beneficial before beginning the dance session especially those involving swift body movements. Hence I will recommend leaving an extra few minutes early for your dance lessons and giving yourself some time before class to warm up your body if its been cold outside. Also correct footwear is important. Investing in dance shoes is beneficial especially if you enjoy dancing and will continue to do so.

As far as improving your dancing is concerned, You need to do three Ps. They are,
1) Practise, 2) Practise and 3) Practise

Enjoy

-Kaush.
Disclaimer: this is my personal opinion. So not necessarily correct. Waiting to hear from others on this.

Good cardio will surely build endurance on the dancefloor, but to improve technique and posture etc, the only thing that will help is practice.
Spend about 5 minutes a day infront of the mirror perfecting just ONE aspect, whether it's shoulder movements, rib cage isolation or the knee bending movement to get the hips going. It will definitely help in the long run. Also, it's true...get out and dance in the salsa clubs or at the practice sessions!